Magnetic coating compositions now in use are generally composed of magnetic fine powder or magnetic metal fine powder such as .gamma.-Fe.sub.2 O.sub.3 and Fe, synthetic resin binder, dispensant, lubricant, and organic solvent. As the synthetic resin binder, nitrocellulose is commonly used because of its abilities to disperse the magnetic powder therein and to provide an adequately hardened layer. Recently, there has arisen a demand for sophisticated magnetic recording media having a higher recording density than before. It is now apparent that conventional nitrocellulose is insufficient with respect to its ability to disperse the magnetic powder to meet such a demand.